1. Field of the Invention
The present invention relates to a technology realized with a storage device using a disk-shaped (circular) storage medium, and more specifically to a technology of setting various parameters for control of seeking, reading and writing data using a head in each unit of the device for the storage medium.
2. Description of the Prior Art
For example, a storage device using a disk-shaped storage medium such as a magnetic disk and an optical disk, etc. has a large storage capacity, accesses data at a high speed, and the cost per storage capacity is relatively low. Therefore, it is widely used in computers, etc. Described below is a magnetic disk storage device as an example of the above mentioned storage device.
A magnetic disk storage device is configured using various IC (integrated circuits). Each IC receives various parameters transferred from an MPU (microprocessor) for controlling the entire system, and each IC functions depending on the settings of the parameters, thereby writing/reading data to and from a magnetic disk.
Recently, various ICs configuring a magnetic disk storage device have been provided with a variety of functions in response to a request to realize a high-performance device and guarantee high reliability. As a result, it is necessary to set a large number of parameters in the ICs to operate the ICs.
Some of these parameters have to be transferred only once when the power is applied to a magnetic disk storage device, and no subsequent transfer is required, and others have to be transferred each time a process is performed with an operation mode switched into a different mode among a data seek (retrieval) mode, a data read mode, and a data write mode.
FIG. 1 is a table of important parameters transmitted from an MPU for each IC of important ICs HDIC, RDC, and SV-DEM forming part of a magnetic disk storage device. The table shown in FIG. 1 contains (i) parameters to be transferred only when the power is applied to a magnetic disk storage device, and (ii) parameters to be transferred each time a process is performed with an operation mode switched into another. Described below are these ICs and parameters set for the ICs.
The HDIC is a head IC, and controls the operations of a magnetic head. The IC practically functions as a preamplifier for amplification of a read signal and a bias current source for a magnetic head when data is read, and as a driver of the magnetic head when data is written. Furthermore, the HDIC has the function of selecting a magnetic head for use actually in writing/reading data from a plurality of magnetic heads.
The HDIC has parameters HBW, LBW, and TADT to be transferred when the power is applied to the system, and parameters HS, IMR, and IW to be transferred when an operation mode is switched into another.
For the parameters HBW and LBW, the upper limit and the lower limit of the passage area of a band pass filter are set to limit the band of a signal read from each magnetic head.
The TADT is a parameter set to solve the problem (thermal asperity) that a resistance value is changed by the influence of the heat generated by the contact between a magnetic head and a magnetic disk when an MR (magneto resistive) element is used as the magnetic head. A threshold is set to detect that a magnetic head touches a magnetic disk based on the voltage value obtained from the magnetic head.
The HS is short for head selection, and is a parameter set to select a head to be used in a newly switched operation mode from a plurality of magnetic heads.
The IMR refers to a sense current for which a bias current value for the selected head is set when data is read.
The IW refers to a write current for which a drive current value for the selected magnetic head is set when data is written.
The RDC refers to an IC of a read channel. The IC is used in a data signal process. When data is read, a data signal, which is an analog signal transmitted from the HDIC, is demodulated based on, for example, the PRML (partial response maximum likelihood) system, and is then decoded. The decoded digital data is converted into a parallel signal. When data is written, the data to be written is encoded and modulated. A data signal, which is an analog signal, is transmitted to the HDIC.
The RDC has parameters R_MODE and W_MODE to be transferred when power is applied to the system, and parameters FIR, FC, Boost, and TBG to be transferred when operation modes are switched.
For the R_MODE, a decoding system is set when data is read.
For the W_MODE, an encoding system is set when data is written.
For the FIR, the number of taps of a digital filter functioning as an equalizer for signal equivalence is set, thereby setting the characteristic of the digital filter.
For the FC and Boost, the cutoff frequency and the amount of boost of an analog filter (high cut or high boost) for limiting the band of an analog signal are respectively set, thereby setting the characteristics of the analog filter.
For the TBG, the frequency to be generated by a time base generator for generating a reference clock for the RDC, that is, the transfer frequency between a magnetic head and a magnetic disk, is set. It is necessary to change the parameter each time an operation mode is switched when data is stored on a magnetic disk using a ZBR (zone bit recording), etc.
An SV-DEMO is an IC of a servo demodulator, and practically processes a signal required to configure the servo for control of the position of a magnetic head according to a data signal which is an analog signal transmitted from the HDIC.
The SV-DEMO has a parameter AGI to be transferred when power is applied to the system, and parameters SSLE, SSLD, SFC, SBT, and SFG to be transferred when operation modes are switched.
For the AGI, an output level of an AGC (automatic gain control) amplifier for amplifying an analog signal is set.
For the SSLE and SSLD, a threshold of the determination condition of 3-value determination performed when a waveform is equalized by the partial response system is set.
For the SFC and SBT, the cutoff frequency and the amount of boost of the filter (high cut or high boost) for determination of the stability and the response time are respectively set, thereby setting the characteristics of the filter.
For the SFG, a frequency generated by a time base generator of the SV-DEMO, that is, the transfer frequency of the data between a magnetic head and a magnetic disk is set. It is also necessary to change this parameter each time operation modes are switched when data is stored on a magnetic disk using the ZBR, etc.
FIG. 2 is a flowchart of the contents of the parameter transferring process performed by the MPU of the conventional magnetic disk storage device.
First, in S1001, the MPU detects that power has been applied to the magnetic disk storage device.
Then, in S1002, the MPU reads the set value of a parameter (for example, the parameter shown in line (i) in FIG. 1) to be rewritten only when power is turned ON from the flash memory (or ROM) storing in advance the set value of each parameter, and transfers the value to a corresponding IC.
In S1003, the MPU reads a parameter (for example, a parameter shown in line (ii) in FIG. 1) to be transferred when operation modes are switched from the flash memory (or ROM), and temporarily stores the parameter in the RAM used by the MPU as work memory. FIG. 3 shows an example of assigning a storage area of the RAM on which the parameter transferred when operation modes are switched is stored, and the set values of the parameters are stored for each IC requiring the setting of the value in the storage area. Then, the MPU reads the initially set value of each parameter, and transfers it to each IC.
In S1004, the MPU instructs each IC to start operating the magnetic disk storage device.
In S1005, the MPU obtains a request for seeking, reading, and writing operations from the system of a computer, etc. which is a host of the magnetic disk storage device.
In S1006, the MPU selects a parameter (for example, a parameter shown in (ii) in FIG. 1) set when operation modes are switched, reads the set value of each of the selected parameters, and transfers it to each IC.
In S1007, the MPU specifies each IC to start an operation at a request obtained in S1005, and then returns back in S1005, and repeats the above mentioned processes.
The MPU in the conventional magnetic disk storage device has realized the transfer of each parameter to each IC by performing the above mentioned processes.
As described above, as various ICs forming a magnetic disk storage device have been assigned a larger number of functions, it is necessary to set a larger number of parameters to operate all these ICs. However, in the process performed by the MPU of the conventional magnetic disk storage device of transferring to each IC a parameter value to be set each time operation modes are switched, the set values of all corresponding parameters are transferred to respective ICs regardless of the difference in contents of the operation requests from the host. Therefore, with an increasing number of parameters, the transfer time of parameter values exceedingly increases, thereby undesirably affecting the response time for an operation request to the magnetic disk storage device.
The present invention has been developed to solve the above mentioned problems, and aims at shortening the response time for an operation request in a storage device using a disk-shaped storage medium.
The disk storage device according to an embodiment of the present invention is based on the disk storage device for seeking, reading, or writing data on a disk-shaped information storage medium using a head.
The disk storage device includes an obtaining unit for obtaining a request for the operation; a determination unit for determining the contents of the request; and a transfer unit for transferring the set value of the parameter, among the parameters for control of the operation, to be changed such that the request for the operation can be satisfied.
With the configuration, depending on the contents of the operation request issued by the host, only the set value of the minimal parameter is transferred to control the operation such that the contents of the request can be satisfied, and the set value of a parameter unnecessary for the control is prevented from being transferred. As a result, the response time to the host for the operation request can be shortened.
With the configuration, the device can further include memory whose storage area includes a plurality of banks for dividing the set values of the parameters corresponding to the contents of the operation request and storing the divided values in the respective banks. The transfer unit can read the set value of the parameter, and transfer it. With the configuration, a data accessing process repeatedly performed on the memory when a parameter set value is read can be performed at a high speed. Therefore, the response time of the disk storage device to the host can be furthermore shortened.
Furthermore, a method of transferring a control parameter according to another embodiment of the present invention is based on the method of transferring a parameter for control of an operation of the disk storage device for performing head seeking, data reading, or data writing operations on a disk-shaped storage medium. The method includes: obtaining a request for the operation; determining the contents of the request; and transferring the set value of the parameter, among the parameters for control of the operation, to be changed such that the request for the operation can be satisfied. Thus, according to this control parameter transferring method, the operation and effect similar to those of the above mentioned disk storage device can be obtained.
With the configuration of the disk storage device according to the present invention, the device can further include a plurality of heads for reading and writing data using the storage medium, and the transfer unit, and the transfer unit can be designed not to transfer a set value of a parameter for control of a selecting process when it is not necessary to change the selection of the head to control the above mentioned operation. Otherwise, the device can further include a head for reading and writing data using the information storage medium, and the transfer unit can be designed not to transfer a set value of a parameter for setting a transfer frequency of data between the head and the storage medium when it is not necessary to change the position of the head on the storage medium to control the above mentioned operation. Among the parameters required to control a requesting operation, some parameters require no change of settings depending on the operation status of the current disk storage device. With the configuration, the transfer of the set value of such a parameter can be suppressed. Therefore, the number of parameters for transfer of set values can be reduced, thereby furthermore shortening the response time from the disk storage device to the host.
In addition, a computer-readable program storage medium storing a control parameter transfer program for directing a computer to perform a controlling process corresponding to the above mentioned method of transferring a control parameter can be designed to direct the computer to read and execute the program. With the configuration, the operation and effect similar to those of the above mentioned disk storage device can be obtained.